For many years, the standard apparatus for performing the evacuation of the pleural cavity was a drainage system known as the "3-bottle set-up" which includes a collection bottle, a water seal bottle and a suction control bottle. A catheter runs from the patient's pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply suction to the pleural cavity to withdraw fluid and air and thereafter discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal also usually prevents the back flow of air into the chest cavity.
Suction pressure is usually provided by a central vacuum supply in a hospital so as to permit withdrawal of fluids such as blood, water and gas from a patient's pleural cavity by establishing a pressure differential between the suction source and the internal pressure in the patient. Such suction pressure (vacuum) and pressure differentials must be precisely maintained because of the dangerous conditions which could result if unduly high or low pressure differentials should occur. However, the hospital suction source typically can vary over time which degrades the suction performance. Also, drainage systems incorporating manometers in the suction control chamber are inconvenient because of the need to add water prior to use, as well as because of their size and weight. In addition, evaporation in the suction control chamber results in suction pressure variations which must be corrected by the addition of more water thereby increasing the maintenance and monitoring time required in the use of such drainage systems.
Also various inefficiencies have existed in the 3-bottle set-up resulting from the many separate components and the large number (usually 16 or 17) of connections. Complications such as pneumothorax may result from the loss of the water seal in the water seal bottle if suction were temporarily disconnected, and undue build-ups of positive pressure could cause tension pneumothorax and possible mediastinal shift. Another serious shortcoming of the 3-bottle set-up is the possibility of incorrect connection and the time necessary to set the system up to monitor its operation.
The 3-bottle set-up lost favor with the introduction of an underwater seal drainage system sold under the name PLEUR-EVAC.RTM. in 1966 by Deknatel Inc. U.S. Pat. Nos. 3,363,626; 3,363,627; 3,559,647; 3,683,913; 3,782,497; 4,258,824; and Re. 29,877 are directed to various aspects of the Pleur-evac.RTM. system which over the years has provided improvements that eliminated various shortcomings of the 3-bottle set-up. These improvements have included the elimination of variations in the 3-bottle set-up that existed between different manufacturers, hospitals and hospital laboratories. A more detailed description of the need for and the proper use of chest drainage devices is presented in the Deknatel Inc. PLEUR-EVAC.RTM. publication entitled "Physiology of the Chest and Thoracic Catheters; Chest Drainage Systems No. 1 of a series from Deknatel" (1985) which is incorporated herein by reference.
Among the features of the PLEUR-EVAC.RTM. underwater seal drainage system which provide its improved performance is a single, pre-formed, self-contained unit that embodies the 3-bottle techniques. The desired values of suction are generally established by the levels of water in the suction control chamber. These levels are filled according to specified values prior to the application of the system to the patient. A special valve referred to as the "High Negativity Valve" is included which is employed when the patient's negativity becomes sufficient to threaten loss of the water seal. Also, a "Positive Pressure Release Valve" in the large arm of the water seal chamber works to prevent a tension pneumothorax when pressure in the large arm of the water seal exceeds a prescribed value because of suction malfunction, accidental clamping or occlusion of the suction tube. The PLEUR-EVAC.RTM. underwater seal drainage system is disposable and helps in the battle to control cross-contamination.
Despite the advantages of the PLEUR-EVAC.RTM. underwater seal drainage system over the 3-bottle set-up and the general acceptance of the device in the medical community, there remains a continuing need to improve the convenience and performance of chest drainage systems and to render such systems compact. As noted above, fluid filled suction control chambers are filled to levels specified by the physician prior to being connected to the patient and the hospital suction system. The levels of suction obtained by such a chest drainage system are somewhat limited by the size (e.g. height) of the chamber required to maintain such suction levels. For high levels of suction, the chamber height required would in some circumstances render the drainage system impractical. In addition, accuracy of such underwater drainage systems is limited in that the fluid chamber employed therein must be constantly monitored visually by observing the liquid level in the respective chambers. Even when gauges are used, they likewise must be constantly monitored. In either case, when the fluid in the chambers evaporates, suction variations can occur which require the addition of more water to compensate for the water loss. All such activity of course is time consuming and is labor intensive.
Because of the size of such devices, they usually present an obstruction between the patient and visitors and the medical staff. As such, it is not uncommon for the device to be knocked over thereby creating the potential for cross-contamination of fluids within the device. These devices, may include some mechanism to minimize cross-contamination if the device falls over on its back, however, there is no protection available if the device falls on its frontside. It is also possible for these units, when knocked over, to become damaged or broken. Because these devices are usually close to the floor when patients are being transported, e.g. between floors of a hospital, it is not uncommon to see a device get broken because they collided with floors, obstructions or when getting on/off elevators.
As a result, the medical staff must take extra care when using such devices so the devices are not inadvertently knocked over or damaged during transportation. If a device is damaged, the medical staff must stabilize the patient, replace the device and clean up the collected fluids that have spilled. This can become even more problematic if the device is being used to collect blood in an autotransfusion process. In addition to the medical staff dealing with the unwanted patient anxiety that may occur, dealing with damaged or broken drainage devices is costly, labor intensive and time consuming. The foregoing also applies to devices that have become cross-contaminated because they are typically replaced by the medical staff.
Other drainage systems or devices have been developed since the introduction of the above described underwater systems to address their perceived shortcomings. One type of drainage device since developed, such as that described in U.S. Pat. No. 5,300,050, uses a waterless pressure regulator as a means for controlling suction pressure and a water filled chamber to establish a seal, the patient seal, between the fluid collection chamber and the suction source. These devices, like the above-described underwater drainage systems, can be damaged during transportation of patients, create an obstruction, and can be knocked over. Also, although these devices may include some protection to minimize cross-contamination if knocked over on their backside, there is no protection if they fall forward.
Another type of drainage device, such as that described in U.S. Pat. Nos. 4,738,671, 4,715,856, 4,544,370, 4,747,844, includes a modulation valve to control the suction flow, and correspondingly the suction pressure being developed, and a one way valve that forms the seal between the suction source and the collection chamber(e.g. the patient seal). In these devices the collection chamber is disposed below the mechanisms for regulating the suction flow and pressure, the mechanism for establishing the patient seal, flow meters and the internal drain and suction lines. These units are complex and involve a large number of parts. Also, because of the direct communication between the seal valve and the collection chamber, the seal valve can come into contact with the collected fluid if the device falls over. These devices, like those described, create an obstruction, can be damaged during transportation of patients and can be knocked over.
Yet another type of device as shown in U.S. Pat. No. 4,605,400, uses a plurality of one way valves to control suction pressure and one, or two one-way valves in series, as a one-way seal between the suction source and the collection chamber. The collection chamber is located below the other controlling parts of the device. A trap is provided between the seal valve(s) and the collection chamber to collect any liquids inadvertently withdrawn through the suction line therebetween. However, there is no barrier between the one-way seal and the suction source and other parts of the device. Thus, if the device is knocked over, collected fluid can flow through and contaminate various parts of the device. Moreover, there is the potential for the collected fluid to be drawn into the suction system. As with the above-described devices, this device can be damaged during patient transport and create an obstruction that can lead to the unit being knocked over.
In sum, it is common for prior art devices to get knocked over, which can have adverse consequences, and for them to get damaged during patient transport. This creates an environment where the medical staff must exercise extra care to avoid unwanted consequences. It also creates a labor intensive, time consuming and expensive environment.
Accordingly, there is a need for an improved device or system as well as methods related thereto for removing gases and liquids from medical patients where suction pressure control and the collection chamber seal does not involve the use of liquids. Further, there is a need for an improved mechanism for venting the collection chamber that is more resistant to cross contamination than prior art devices and systems. Additionally, there is a need for improved devices that are compact in size and are resistant to overturning as compared to prior art devices.